/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.servlet.view.xml;

import com.fasterxml.jackson.annotation.JsonView;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.validation.BindingResult;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.view.json.AbstractJackson2View;

import java.util.Map;

/**
 * Spring MVC {@link View} that renders XML content by serializing the model for the current request
 * using <a href="https://github.com/FasterXML/jackson">Jackson 2's</a> {@link XmlMapper}.
 *
 * <p>The Object to be serialized is supplied as a parameter in the model. The first serializable
 * entry is used. Users can either specify a specific entry in the model via the
 * {@link #setModelKey(String) sourceKey} property.
 *
 * <p>The default constructor uses the default configuration provided by {@link Jackson2ObjectMapperBuilder}.
 *
 * <p>Compatible with Jackson 2.6 and higher, as of Spring 4.3.
 *
 * @author Sebastien Deleuze
 * @see org.springframework.web.servlet.view.json.MappingJackson2JsonView
 * @since 4.1
 */
public class MappingJackson2XmlView extends AbstractJackson2View {

    /**
     * The default content type for the view.
     */
    public static final String DEFAULT_CONTENT_TYPE = "application/xml";


    @Nullable
    private String modelKey;


    /**
     * Construct a new {@code MappingJackson2XmlView} using default configuration
     * provided by {@link Jackson2ObjectMapperBuilder} and setting the content type
     * to {@code application/xml}.
     */
    public MappingJackson2XmlView() {
        super(Jackson2ObjectMapperBuilder.xml().build(), DEFAULT_CONTENT_TYPE);
    }

    /**
     * Construct a new {@code MappingJackson2XmlView} using the provided {@link XmlMapper}
     * and setting the content type to {@code application/xml}.
     *
     * @since 4.2.1
     */
    public MappingJackson2XmlView(XmlMapper xmlMapper) {
        super(xmlMapper, DEFAULT_CONTENT_TYPE);
    }


    @Override
    public void setModelKey(String modelKey) {
        this.modelKey = modelKey;
    }

    @Override
    protected Object filterModel(Map<String, Object> model) {
        Object value = null;
        if (this.modelKey != null) {
            value = model.get(this.modelKey);
            if (value == null) {
                throw new IllegalStateException(
                        "Model contains no object with key [" + this.modelKey + "]");
            }
        }
        else {
            for (Map.Entry<String, Object> entry : model.entrySet()) {
                if (!(entry.getValue() instanceof BindingResult) && !entry.getKey().equals(JsonView.class.getName())) {
                    if (value != null) {
                        throw new IllegalStateException("Model contains more than one object to render, only one is supported");
                    }
                    value = entry.getValue();
                }
            }
        }
        Assert.state(value != null, "Model contains no object to render");
        return value;
    }

}
